Those do fail though not that often, might even be repairable but since they're only about 20 euro to buy I wouldn't bother trying.
If you feel comfortable replacing a normal electric switch, this is almost as straightforward to replace - if you can buy the exact same model it's a case of noting down the positions of the wires and moving them to the new one - make sure the power is off first of course. You should go to an electrical supplies place where electricians themselves go, rather than B&Q or Woodies etc., it'll be cheaper and they'll have the right model.